From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753878Ab3JaKn4 (ORCPT ); Thu, 31 Oct 2013 06:43:56 -0400 Received: from 1.mo4.mail-out.ovh.net ([178.33.248.196]:45295 "EHLO mo4.mail-out.ovh.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753295Ab3JaKnz (ORCPT ); Thu, 31 Oct 2013 06:43:55 -0400 Date: Thu, 31 Oct 2013 11:45:49 +0100 From: Jean-Christophe PLAGNIOL-VILLARD To: David Herrmann Cc: linux-fbdev@vger.kernel.org, James Bates , linux-kernel@vger.kernel.org, Tomi Valkeinen , James Bates Subject: Re: [PATCH v2] efifb: prevent null-deref when iterating dmi_list Message-ID: <20131031104549.GZ18477@ns203013.ovh.net> References: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> X-PGP-Key: http://uboot.jcrosoft.org/plagnioj.asc X-PGP-key-fingerprint: 6309 2BBA 16C8 3A07 1772 CC24 DEFC FFA3 279C CE7C User-Agent: Mutt/1.5.21 (2010-09-15) X-Ovh-Tracer-Id: 3775986814699940813 X-Ovh-Remote: 91.121.171.124 (ns203013.ovh.net) X-Ovh-Local: 213.186.33.20 (ns0.ovh.net) X-OVH-SPAMSTATE: OK X-OVH-SPAMSCORE: -100 X-OVH-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeeiledrgeekucetufdoteggodetrfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-Spam-Check: DONE|U 0.5/N X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeeiledrgeekucetufdoteggodetrfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 18:40 Wed 02 Oct , David Herrmann wrote: > The dmi_list array is initialized using gnu designated initializers, and > therefore may contain fewer explicitly defined entries as there are > elements in it. This is because the enum above with M_xyz constants > contains more items than the designated initializer. Those elements not > explicitly initialized are implicitly set to 0. > > Now efifb_setup() loops through all these array elements, and performs > a strcmp on each item. For non explicitly initialized elements this will > be a null pointer: > > This patch swaps the check order in the if statement, thus checks first > whether dmi_list[i].base is null. > > Signed-off-by: James Bates > Signed-off-by: David Herrmann with the simpleDRM arriving next merge I'm wondering if we need to keep it? Best Regaards, J. > --- > Hi > > As James didn't respond to the last emails, I just rebased the patch and resent > it. The efi M_xyz constants were moved to x86-sysfb so if anyone wants to remove > unused bits, please send a separate patch to LKML and x86-ML. This patch just > fixes the NULL-deref. > > Thanks > David > > drivers/video/efifb.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c > index 7f9ff75..fcb9500 100644 > --- a/drivers/video/efifb.c > +++ b/drivers/video/efifb.c > @@ -108,8 +108,8 @@ static int efifb_setup(char *options) > if (!*this_opt) continue; > > for (i = 0; i < M_UNKNOWN; i++) { > - if (!strcmp(this_opt, efifb_dmi_list[i].optname) && > - efifb_dmi_list[i].base != 0) { > + if (efifb_dmi_list[i].base != 0 && > + !strcmp(this_opt, efifb_dmi_list[i].optname)) { > screen_info.lfb_base = efifb_dmi_list[i].base; > screen_info.lfb_linelength = efifb_dmi_list[i].stride; > screen_info.lfb_width = efifb_dmi_list[i].width; > -- > 1.8.4 > From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jean-Christophe PLAGNIOL-VILLARD Date: Thu, 31 Oct 2013 10:45:49 +0000 Subject: Re: [PATCH v2] efifb: prevent null-deref when iterating dmi_list Message-Id: <20131031104549.GZ18477@ns203013.ovh.net> List-Id: References: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> In-Reply-To: <1380732056-5387-1-git-send-email-dh.herrmann@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: David Herrmann Cc: linux-fbdev@vger.kernel.org, James Bates , linux-kernel@vger.kernel.org, Tomi Valkeinen , James Bates On 18:40 Wed 02 Oct , David Herrmann wrote: > The dmi_list array is initialized using gnu designated initializers, and > therefore may contain fewer explicitly defined entries as there are > elements in it. This is because the enum above with M_xyz constants > contains more items than the designated initializer. Those elements not > explicitly initialized are implicitly set to 0. > > Now efifb_setup() loops through all these array elements, and performs > a strcmp on each item. For non explicitly initialized elements this will > be a null pointer: > > This patch swaps the check order in the if statement, thus checks first > whether dmi_list[i].base is null. > > Signed-off-by: James Bates > Signed-off-by: David Herrmann with the simpleDRM arriving next merge I'm wondering if we need to keep it? Best Regaards, J. > --- > Hi > > As James didn't respond to the last emails, I just rebased the patch and resent > it. The efi M_xyz constants were moved to x86-sysfb so if anyone wants to remove > unused bits, please send a separate patch to LKML and x86-ML. This patch just > fixes the NULL-deref. > > Thanks > David > > drivers/video/efifb.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/video/efifb.c b/drivers/video/efifb.c > index 7f9ff75..fcb9500 100644 > --- a/drivers/video/efifb.c > +++ b/drivers/video/efifb.c > @@ -108,8 +108,8 @@ static int efifb_setup(char *options) > if (!*this_opt) continue; > > for (i = 0; i < M_UNKNOWN; i++) { > - if (!strcmp(this_opt, efifb_dmi_list[i].optname) && > - efifb_dmi_list[i].base != 0) { > + if (efifb_dmi_list[i].base != 0 && > + !strcmp(this_opt, efifb_dmi_list[i].optname)) { > screen_info.lfb_base = efifb_dmi_list[i].base; > screen_info.lfb_linelength = efifb_dmi_list[i].stride; > screen_info.lfb_width = efifb_dmi_list[i].width; > -- > 1.8.4 >